Conventional spark plugs for spark ignition engines have a long stretched-out spark plug body, in which a central section carries an external thread, and one end has two electrodes bordering a spark gap. As a rule, one of these electrodes is arranged on a longitudinal axis of the spark plug body, and can be exposed to a high voltage, while the other electrode is a ground electrode that extends like a hook from the spark plug body and around the high-voltage electrode. Both electrodes combined define a spark gap lying on the axis of the spark plug body.
When such a conventional spark plug is screwed into a cylinder head, the rotational orientation assumed by the completely mounted spark plug is absolutely random. In internal combustion engines with homogeneous combustion, spark plug orientation is unimportant with respect to combustion behavior. However, in internal combustion engines with direct injection, it was determined that the combustion behavior of a combustion chamber can vary depending on the spark plug orientation.
At least one object of the present invention is to provide a spark plug and cylinder head for an internal combustion engine with direct injection to ensure a uniform combustion behavior by all cylinders in the internal combustion engine. In addition, other objects, desirable features, and characteristics will become apparent from the subsequent summary and detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.